extract only alpha characters from a string

[poe]

i will have a string that is for sports scores and is shown  as:

outcome(w,l,t,so,nd) team score : opp score

so it would look like:
[a-z] [0-9] : [0-9]

ie. w14:3
OR l16:21
OR so4:3
OR t6:6
etc...


i want to add a `:` after the outcome

ie..  w:7:3
how do i add a : after the alpha charactert(s)

[sinisake]

Can be done on this way:
[code]
<?php
$stringi="w14:3";
$patern="^[a-z]+";
if(eregi($patern,$stringi,$match)){
$match=implode("",$match);
$replace=$match.":";
$stringi=eregi_replace($match,$replace,$stringi);
echo ($stringi);
}

?>
[/code]